Illinois’ population stayed fairly flat into 2025, following a national trend of low growth due to a historic decrease in net international immigration, according to new figures released on Tuesday by the Census Bureau.
The state’s population increased by 16,108, or 0.001%, to 12,719,141, from July 2024 to July 2025, keeping it the sixth most populous state.
Nationwide, the population grew by 1.8 million, or 0.5%, the slowest rate since the historically low growth rate of 0.2% during the COVID pandemic in 2021. The slowdown also comes after a bump in growth in 2024, when the country added 3 million people and grew by 1%, the fastest annual population growth rate since 2006.
“With births and deaths remaining relatively stable compared to the prior year, the sharp decline in net international migration is the main reason for the slower growth rate we see today,” said Christine Hartley, assistant division chief for Estimates and Projections at the Census Bureau.
Net international migration was 1.3 million, a drop of more than half from 2.7 million the year before, due primarily to the Trump administration’s crackdown on immigration, experts said. If current trends continue, net international migration is projected to drop by 1 million more by July 2026.
“The big story nationally is about international immigration being down,” said Christine Percheski, associate professor of sociology and faculty fellow at Northwestern University’s Institute for Policy Research in Evanston. “We see that in Illinois as well.”
While Illinois has typically had more residents move out to other states than move in in recent years, international immigration has made up for most of the loss.
But with the administration of President Donald Trump restricting legal immigration and U.S. Immigration and Customs Enforcement and U.S. Customs and Border Protection ramping up arrests of people accused of illegal immigration, fewer foreigners are arriving.
“Population growing or shrinking isn’t necessarily bad, it’s about how we respond,” Percheski said. “Stability is fine. It’s really big changes in population in a short time that creates big challenges. But we’ve been seeing modest changes in Illinois for quite a while.”
The Midwest was the only region where all states gained population. After experiencing population decline in 2021 and small growth in 2022, the Midwest’s population grew solidly in the past three years, census officials said.
The Midwest also saw slightly positive net domestic migration for the first time this decade — a turnaround from substantial losses in 2021 and 2022.
South Carolina was the fastest-growing state, gaining almost 80,000, driven by domestic net migration, followed by Idaho, North Carolina, Texas and Utah.
The immigration crackdown is likely to deter more immigrants from participating in the census, reducing federal funding to the state for essentials like roads, schools and libraries, said Dr. Kathleen Yang-Clayton, senior visiting scholar and civic invitation fellow at the Chaddick Institute at DePaul University in Chicago.
She urged working now to gain immigrants’ trust in participating in the census.
“The hard-to-count folks are most impacted by an undercount,” she said. “In the end, laying eyes on people … is going to take a lot more trust because of what’s happening with ICE.”